1. Field
One embodiment of the invention relates to a technology for increasing resolution of an image and, more particularly, to a technology for correcting an image with increased resolution.
2. Description of the Related Art
Televisions have been used to display video images. A television performs high-resolution (resolution increasing) processing for converting a standard definition (SD) image to a high-resolution and high definition (HD) image, or double-speed processing for smooth display of a moving video image, i.e., moving-image improvement. After the processing, to further improve image quality, image corrections such as gamma correction and white balance adjustment are performed on the image subjected to the high-resolution processing or the moving-image improvement.
For example, Japanese Patent Application Publication (KOKAI) Nos. 2002-230574, H10-191208, and 2006-279262 disclose technologies for such image corrections performed on an image subjected to the high-resolution processing or the moving-image improvement.
An old-fashioned television does not have the function of performing the double-speed processing as well as the high-resolution processing according to the super resolution technology as described above. Therefore, when an image correction is performed in either the moving-image improvement or the high-resolution processing, the processing result does not adversely affect image quality.
If it is assumed that the moving-image improvement and super-resolution processing are performed by a television as, for example, in the case where the moving-image improvement is performed after white balance adjustment in the super-resolution processing, the pixel value of a high-luminance pixel exceeds the dynamic range due to white balance adjustment in the moving-image improvement. More specifically, even if white balance adjustment is originally performed appropriately within the dynamic range, when white balance adjustment is performed on the high-luminance pixel in a range R exceeding a certain threshold after white balance adjustment in the super-resolution processing, its pixel value exceeds the maximum value of the dynamic range. This results in “clipped highlights”. That is, if a television, which is capable of performing the moving-image improvement and the super-resolution processing and has the function of performing a similar correction process in both of them, performs the correction process in the high-resolution processing, an image is erroneously processed by the moving-image improvement.